Just a little blog for posting various creations for the BECMI / Rules Cyclopedia edition of Dungeons and Dragons. All hail the Red Box!
Updated whenever possible with a little something, whether a monster or spell or item or just a little list of whatevers.

I'd started typing a response; then decided it was entirely too long for a comment and moved it over here *grins*

For dragons at least, they have the twin stumbling-blocks of reproduction and adventurers --

My dragons reproduce semi-regularly, and spawn many offspring at a time; but those offspring are weak and puny for a long period and are picked off with impunity by many other creatures, because the adult dragons are indifferent to the fates of all but a selected handful of "best of breed" youngsters. The remainder are turned loose on the countryside, but in a world of many critters (and people!) happy to pick off even a tiny dragon, their odds of survival are low in the extreme.

(Granted, any that do survive are canny and powerful blighters in their own right by the sheer dint of having defeated the odds stacked against them ... so the habit still serve the draconic species tolerably well, in a way.)

Those offspring that a dragon retains aren't exactly exempt from fatalities, either. Even ignoring the possibility of being picked off by adventurers -- and more on that subject shortly -- the dragonets may be killed by a displeased parent, or even their own siblings. Competition can be fierce and deadly for the lion's share of parental attention.

The oldest and strongest dragons -- those who by rights would be the most capable of dealing with the largest numbers of selected offspring -- are no longer properly fertile. Males cannot reproduce without magical assistance, and the females, instead of proper offspring, begin to produce eggs that hatch out into various subdraconic "servitor" humanoids.

Adventurers are the other side of the coin for "dragon control". Every lout who swings a sword or casts a cantrip dreams of the day that they can go after a dragon. Dragons are the Big Game, awesome enough to add immensely to one's reputation but quite utterly predictable in many ways and therefore easier to deal with than, say, major elementals. They hoard treasure, are a source of dragon-stones (for even more treasure), and even the carcases are valuable. Dragon hunting more than justifies the risks involved in the eyes of many, and even the more powerful breeds are not completely immune to the hunt -- they simply attract the more powerful adventurers.

And if a dragon survives all of this, if it lives to many Hit Dice and a hoard of magic it can use, swarms of minions and a vast territory?

Now not only does it have the chance of adventurers arriving on the doorstep of its lair, its now the potential target of other elder dragons eager to get its slice of the resource-and-reputation pie ...